It's a valid question. If we had something like phasers instead of firearms, I'd be more than happy to use those exclusively. The problem is we don't really have a good alternative. Tasers that shoot tend to be one shot solutions, and even then they don't always bring down targets, or they might prove as lethal. Rubber bullets you can fire multiple of, but they could cause serious damage too, especially if shot in succession, and there is no guarantee of taking the target down. There just isn't a solid alternative right now.

Not to offer a complete solution: Lasers, and pervasive societal warnings about the danger of lasers.

Why not defend yourself with a towel??

a towel isn't a good defensive weapon. a firearm isn't so good either. it's a great offensive weapon though.